/**
 * 
 */
HTMLElement.prototype.insertAfter = function(newElement, targetElement) { //在一个dom节点后插入一个新dom节点
		var parent = targetElement.parentNode;
		if(parent.lastChild == targetElement) {
			parent.appendChild(newElement);
		} else {
			parent.insertBefore(newElement, targetElement.nextSibling);
		}
	}